Sorry, I was on vacation, so I didn't notice your post.
The idea is that you make a post. Then you make a separate post to ask for feedback, with the tag #writingfeedback. In that post you promise to share the reward or promise some other compensation for the feedback you get. Since the timeframe for getting a reward is short, the feedback also should be gotten within some 12 hours. This doesn't really work unless someone keeps an eye on the tag. Hopefully some day you will get notifications on tags too, so this experiment could work better.